May be acquired from diverse environmental sources (i.e. tap water).
Patients with chronic lung disease may be colonized (i.e. CF patients or patients with chronic tracheotomies).
Must distinguish colonization from clinically significant infection
Most common reason for isolation is colonization of the respiratory tract.
Most common true infections - blood stream infection (usually from vascular catheter) and pneumonia.
Other manifestations rare (endocarditis)
May require contact precautions
True pneumonia more likely in ICU and oncology patients, and after/during treatment with broad spectrum antimicrobial use.
